The invention is related to a method for adjusting a flexer station for the pre-treatment of metal sheets before their rounding, wherein inside of the flexer station a target impact position of the metal sheet on a measurement plate serves as a reference for the adjustment of at least an adjustable element of the flexer station. Furthermore, the invention is related to a use of the method for welding can bodies. Furthermore, the invention is related to a flexer station with at least an adjustable flexer element. Furthermore, the invention is related to a rounding apparatus with such a flexer station and a welding device for manufacturing can bodies with such a rounding apparatus.